Film drier



.tendency to the film to curl.

Patented Mar. 14, 1939 UNITED STATES PATENT OFFICE Agfa AnscoCorporation, Binghamton, corporation of New York N. Y., a

No Drawing. Application June 22, 1937, Serial No. 149,696

6 Claims.

The present invention relates to a composition for effecting the rapiddrying of photographic films.

It has been found advantageous to rapidly dry photographic negativesafter the washing treatment designed to remove substances carried overfrom the fixing bath as such drying has the effect to lessen theduration of treatment. Rapid drying by the application of elevatedtemperatures is, of course, more or less hazardous because of thesusceptibility of the emulsion to injuries and to the liquification ofthe gelatine layer at elevated temperatures. The practice has,therefore, been developed of using low boiling, water miscible solventsfor removing the water carried by the film. Ethyl alcohol was originallyused as such a solvent. Ethyl alcohol, however, has the disadvantagethat it causes streaking or clouding of the film. Methy alcohol is lessopen to this objection and for this reason ethyl alcohol has to a greatextent been supplanted by methyl alcohol. Methyl alcohol, on the otherhand, has the drawback that it has a solvent action on the film base andthereby causes a softening and a permanent swelling of the base, whichimparts a decided It is, therefore, manifest that methyl alcohol doesnot measure up to the practical requirements of the photographic art.

The object of the present invention is to provide a film drier whichwill cause a rapid drying of the film without a streaking of the filmand without imparting any substantial softening or curling propensitiesto the film.

My rapid film drier is a composition essentially comprising a.dehydrating and a hardening agent to which the film and emulsion areinert, such as a low molecular weight aliphatic alcohol and a substancecapable of hardening the gelatine layer. As the low molecular weightalcohol, which has the function of removing the water as by forming anazeotropic mixture therewith, I may use such alcohols as ethyl alcohol,isopropyl alcohol and the like either alone or in admixture with eachother. Different hardening agents for gelatine such as formaldehyde,acetaldehyde, tannic acid, synthetic tanning agents, for example thosecomprising thiophenol such as that sold under the trade name Katanol andthe like may be utilized, but for best results I recommend theutilization of formaldehyde. Generally the formaldehyde is employed inthe form of a 40% solution in water.

While the principal and essential components of my drier are adehydrating agent and a hardening agent, I find it advantageous to alsoinclude with said components a polyhydric alcohol or another softeningagent such as glycerine, glycol, diethylene glycol and the like. Theaction of the polyhydric alcohol is not only to increase the flexibilityof the hardened gelatine layer but it has been found that its presencein the film drier counteracts the tendency of the film to show blushingor to become cloudy, especially if the drying is carried on in anatmosphere of low relative humidity or at higher temperature.

Other components may also be incorporated in the composition. Forinstance it is often found desirable to cover the objectionable odor offormaldehyde and therefore to impart to the composition a pleasant odorby adding thereto a substance such as amyl acetate, essential oils andthe like. Water may also be added to the composition, if desired. Thequantity of water in no case, however, should exceed the quantity ofdehydrating agent in the composition.

My invention is further illustrated by the following examples althoughit is to be understood that my invention is not restricted to theseexamples. Parts are by Parts Methyl alcohol 100 Formaldehyde 40% 10Glycerine C. P 1,2

2 Methyl alcohol 67 Isopropyl alcohol 99% 33 Diethylene glycol 1.8Formaldehyde 40% 10 Oil cinnamon .005 Oil nutmeg .005 Terpinol .02

Methyl alcohol 100 Water 9 Formaldehyde 40%-"--. 4.5 Glycerine C. P 1.2Amyl acetate .6

4 Ethyl alcohol 100 Formaldehyde 40% 5 Ethylene glycol l0 Amyl acetate.5

The treatment baths of the present invention are used according to theconventional practice of the art, that is the film, after a thoroughwashing to remove salts carried over from the fixing bath, is placed ina receptacle containing the rapid drying solution. 'The ,fllmispermitted to remain in said solution for a period varying from 1 to 5minutes. The film is then subjected to the action of theatmospherewhereupon the residual moisture and drying agents are evaporated. Ifdesired, the evaporation of the moisture may be considerably acceleratedby subjecting the film to the action of hot air.

Treatment baths according'to the present invention havebeenfound to veryrapidly remove moisture carried by the film without the film sufferinganyinjuries as theresult of being suby it can'be seen that saidcompositions possess par ticularadvantages especially when compared tojected to said treatment baths. Thus the film is not streaked as is thecase when ethyl alcohol in a concentrated state is employed per se as aI drier.

tendency to curl. Inasmuch as the compositions of the present inventionmay be made up by the very simple expedient of mixing. the componentsthereof, and inasmuch as they produce the de- Nordo'es the film showbrittleness or any sired result without injury to the film in any way,

the treating baths usedheretofore.

What I claim is:

l. A rapid film drier containing as its three essential components avolatile low -molecular' weight aliphatic alcohol, an aliphaticpolyhydric alcohol and an agent capable of hardening or tanninggelatine, said first alcohol being the predominant component of thecomposition any waterimmiscible oil in the composition being present invery small amounts, said composition remaining homogeneous afterextended use.

2. A rapid film drier containingas its three essential components ethylalcohol, a polyhydric alcohol and aqucousformaldehyde, the ethyl alcoholbeing the predominant component of said composition any water-immiscibleoilin the. composition being present in very small amounts, saidcomposition remaining homogeneous after extended use.

3. A rapid film drier consisting of ethyl alcohol,

a polyhydric alcohol selected from the class con-,

sisting of 'a'glycerine and glycol, aqueous formaldehyde and a substancefor imparting a pleasant odor to the composition, the ethyl alcoholbeing the predominant component or the. composition any water-immiscibleoil in the composition being present in very small amounts, said icomposition remaining homogeneous after exsaid composition remaininghomogeneous after extended use. l l 5. A rapid film drier composition,consisting of 7 Parts Methyl alcohol 100 Water 9 Formaldehyde 40% 4.5 IGlycerine C. P y 1.2 Amyl acetate .6

said: composition remaining, homogeneous after 1 extended use. I

' 6'.-A rapid film drier compositiomconsisting of Parts Ethyl o ol I 100Formaldehyde 40% 5 Ethylene glycol e 10 g y Amyl acetate .5

said composition remaining homogeneousafter extended use; I

HOWARD O. BODINE.

